In oilfield characterization, DFA has been mainly performed on a wireline platform and in openhole environments with fluid sampling tools such as Schlumberger's Modular Dynamic Tester (MDT) tool. For example, the Optical Fluid Analyzer (OFA), the Live Fluid Analyzer (LFA), and the Composition Fluid Analyzer (CFA) family of tools from Schlumberger performs composition analysis by optical spectroscopy.
DFA provides real time information on fluid properties which can be used to decide when the sample is worth taking and retrieving to the surface. The OFA, LFA, CFA family, for example, can perform an analysis of the level of contamination of the sampled fluid by the drilling mud having seeped into the formation. Based on this information, the engineer in charge of running the tool can decide whether the sample is worth taking or not, and thus adjust the pumping condition/time to improve sample quality.
DFA can also be used for the profiling of fluid properties without taking samples. Because the number of bottles on a tool string is limited, providing sample analysis without retrieving the sample to the surface makes it possible to increase the number of stations and have a very precise knowledge of the gradient of fluid properties as a function of depth. For example, on the same job, there can be one DFA station every 50 cm to obtain information about fluid properties in the formation for a better understanding of fluid communication within the formation (e.g. compartmentalization identification).
Currently, on a wireline platform, the downhole instrument sends back to the surface the raw data (optical absorption, fluid density, viscosity, pH, etc.). Thereafter, the interpretation of the data relies on algorithms implemented in the surface acquisition system resident at the surface. Some algorithms still require human interpretation and adjustment of parameters at the surface. In addition, decisions regarding the sampling process, tool/pump control and the like also rely on human input at the surface.